I agree with Jimmyhad, looks like a superspeed, if that's a D3 on the bottom that should be a 3rd quarter of 1958. To lightly clean the old gillettes I have, I use a touch of dawn dish soap and some water, let it soak a little while then use an old toothbrush to see if the little bit of gunk will come off. Any further than that I have no idea what the guys do that restore them.